Chemical tagging with APOGEE: discovery of a large population of N-rich stars in the inner Galaxy

Autor: Annie C. Robin, Ralph Schönrich, Michael F. Skrutskie, Melissa Ness, M. Schultheis, Gail Zasowski, Fred Hearty, Courtney R. Epstein, Jennifer Sobeck, Robert W. O'Connell, David L. Nidever, D. A. García-Hernández, Katia Cunha, Carlos Allende Prieto, Timothy C. Beers, Demitri Muna, Cristina Chiappini, Jennifer A. Johnson, Matthew Shetrone, Steven R. Majewski, Donald P. Schneider, Verne V. Smith, Kaike Pan, John C. Wilson, J. Ted Mackereth, Szabolcs Mészáros, Sara Lucatello, Karen Kinemuchi, Ricardo Carrera, S. Drew Chojnowski, Jon A. Holtzman, Peter M. Frinchaboy, Arturo Manchado, Sarah L. Martell, Friedrich Anders, Daniel Oravetz, Ana G. Pérez, Duy Cuong Nguyen, Ricardo P. Schiavon, Marc H. Pinsonneault, Rob A. Williams, Olga Zamora, Nate Bastian, Dmitry Bizyaev, Audrey Simmons
Přispěvatelé: Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), ISO Data Centre (ESA - Espagne), European Space Agency (ESA), J. A. Baker Institute, Cornell University [New York], Department of Astronomy (Ohio State University), Ohio State University [Columbus] (OSU), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)
Rok vydání: 2017
Předmět:
Zdroj: Monthly Notices of the Royal Astronomical Society
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2016, 465 (1), pp.501-524. ⟨10.1093/mnras/stw2162⟩
NASA Astrophysics Data System
ISSN: 0035-8711
1365-2966
Popis: Formation of globular clusters (GCs), the Galactic bulge, or galaxy bulges in general, are important unsolved problems in Galactic astronomy. Homogeneous infrared observations of large samples of stars belonging to GCs and the Galactic bulge field are one of the best ways to study these problems. We report the discovery by APOGEE of a population of field stars in the inner Galaxy with abundances of N, C, and Al that are typically found in GC stars. The newly discovered stars have high [N/Fe], which is correlated with [Al/Fe] and anti-correlated with [C/Fe]. They are homogeneously distributed across, and kinematically indistinguishable from, other field stars in the same volume. Their metallicity distribution is seemingly unimodal, peaking at [Fe/H]~-1, thus being in disagreement with that of the Galactic GC system. Our results can be understood in terms of different scenarios. N-rich stars could be former members of dissolved GCs, in which case the mass in destroyed GCs exceeds that of the surviving GC system by a factor of ~8. In that scenario, the total mass contained in so-called "first-generation" stars cannot be larger than that in "second-generation" stars by more than a factor of ~9 and was certainly smaller. Conversely, our results may imply the absence of a mandatory genetic link between "second generation" stars and GCs. Last, but not least, N-rich stars could be the oldest stars in the Galaxy, the by-products of chemical enrichment by the first stellar generations formed in the heart of the Galaxy.
Comment: 29 pages, 9 Figures. Submitted to MNRAS, revised after second referee pass
Databáze: OpenAIRE
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